This final chapter has several purposes. Most importantly, it ties together concepts and skills presented in previous chapters and applies these concepts very specifically to reading medical journal articles. Throughout the text, we have attempted to illustrate the strengths and weaknesses of some of the studies discussed, but this chapter focuses specifically on those attributes of a study that indicate whether we, as readers of the medical literature, can use the results with confidence. The chapter begins with a brief summary of major types of medical studies. Next, we examine the anatomy of a typical journal article in detail, and we discuss the contents of each component—abstract or summary, introduction, methods, results, discussion, and conclusions. In this examination, we also point out common shortcomings, sources of bias, and threats to the validity of studies.
Clinicians read the literature for many different reasons. Some articles are of interest because you want only to be aware of advances in a field. In these instances, you may decide to skim the article with little interest in how the study was designed and carried out. In such cases, it may be possible to depend on experts in the field who write review articles to provide a relatively superficial level of information. On other occasions, however, you want to know whether the conclusions of the study are valid, perhaps so that they can be used to determine patient care or to plan a research project. In these situations, you need to read and evaluate the article with a critical eye in order to detect poorly done studies that arrive at unwarranted conclusions.
To assist readers in their critical reviews, we present a checklist for evaluating the validity of a journal article. The checklist notes some of the characteristics of a well-designed and well-written article. The checklist is based on experiences of previous edition authors with medical students, house staff, journal clubs, and interactions with physician colleagues. It also reflects the opinions expressed in an article describing how journal editors and statisticians can interact to improve the quality of published medical research (Marks et al, 1988). A number of authors have found that only a minority of published studies meet the criteria for scientific adequacy. The checklist should assist you in using your time most effectively by allowing you to differentiate valid articles from poorly done studies so that you can concentrate on the more productive ones.
Two guidelines recently published increase our optimism that the quality of the published literature will continue to improve. The International Conference on Harmonization (ICH) E9 guideline “Statistical Principles for Clinical Trials” (1999) addresses issues of statistical methodology in the design, conduct, analysis, and evaluation of clinical trials. Application of the principles is intended to facilitate the general acceptance of analyses and conclusions drawn from clinical trials.
The International Committee of Medical Journal ...